Rosie O'Donnell's 17-year-old daughter, Chelsea O'Donnell, is missing in New York and has been for a week now.

"Nyack, New York police authorities have been looking for her in the Rockland County area since Sunday, August 16. She was last seen Tuesday, August 11," a statement on the 53-year-old comedian's website reads. "She was wearing a black sweatshirt hoodie, dark ripped blue jeans, women's grey converse sneakers and a black backpack. Chelsea has a large tattoo on her right side of a dream catcher with the word 'Breathe.' She left home with her 6 month old therapy dog named Bear. The dog is a 9 lbs brown and black terrier. Chelsea stopped taking her medicine and is in need of medical attention."

A source close to the family confirms to ET that the family does not suspect foul play nor fears that Chelsea was abducted. They believe she ran away from home. Although the source does not know the specific medication she is on, they did confirm that it was for treating a mental health issue.

"Chelsea, like millions of people, lives with mental illness. It has been a difficult road for Chelsea and her family and they just want her back safe," Rosie's rep, Cindi Berger, tells ET.

Rosie also tweeted a photo of Chelsea and her dog on Tuesday. "Chelsea and her dog bear -- last seen in Nyack, NY -- may be in NYC -- please call 845-358-0206 or 911," she wrote.

Chelsea is Rosie's adopted daughter with her ex-wife, Kelli Carpenter.

In March, Chelsea's biological mother claimed to the National Enquirer that Rosie allegedly took advantage of her drug addiction to "steal" her child away from her in 1997. "I believe Rosie O'Donnell knew that I was in no condition to sign away my parental rights to my daughter!" Deanna Micoley, 37, told the tabloid. Micoley, who lives in Wisconsin, also claimed that she and Chelsea have been in touch through Facebook and text messages, and that Chelsea said she had "issues" with Rosie.

Rosie has five children -- Parker, Chelsea, Blake, Vivienne, and Dakota.